Biomethanation - Page 4

The Biogas technology has wide applications in both developing and developed countries. China is the world leader in implementing biogas digester based programs. In 1970, they constructed the first large-scale biogas plant including seven million digesters. This plant provided energy (from biogas) to approximately 25 million people.

Another major user of biogas digesters is India; where roughly 280 000 small-scale digesters were installed in 1985. For smaller applications, the forms of biomass used in anaerobic digesters can be animal manure, kitchen wastes, water hyacinths, human feces, and straw. There have been larger industrial countries where sizable digesters have been built, using input products such sewage sludge, municipal wastes, industrial organic-waste (e.g. food processing, dairy, brewing, paper, pulp, pharmaceutical, and alcohol production), and crop by-products (e.g. wheat and alfalfa). Additionally, the biogas generated from a landfill is collected and used for energy generation.

Biogas process is a way to treat different types of waste in an environmentally friendly way while having the additional benefit that it produces renewable energy.

The anaerobic digestion process is mainly utilized to treat four groups of waste:

1. Sludge produced during the aerobic treatment of municipal sewage. The biogas created during digestion process can partly cover the amount of energy consumed by the sewage treatment plant itself.

2. Wastewater generated from industry (e.g. food and fermentation industry) is treated in biogas plants before discharge into an aquatic environment or a sewage system. This type of wastewater contains a high concentration of pollutants; therefore it can not be discharged directly to the environmental surroundings. The biogas resulting from the treatment process can compensate in full the amount of energy the consumed directly by the process.

3. Animal manure is used as biomass in the biogas plant to generate energy and to improve the fertilizer quality. Anaerobic digestion of manure helps to remove the pathogens which may be present in the raw manure, thereby improving the quality of the fertilizers. This application of the process is increasing due to the restrictive rules concerning the usage, distribution, and storage of manure.

4. Organic waste from households is utilized in the biogas plant for energy production. The goal is to reduce the amount of waste directed to landfills and incineration plants, and while utilizing the nutrients within this material for agricultural purposes. The energy yield of Municipal Solid Waste (MSW) using anaerobic digestion process is 80-160 kWh/ton of MSW. In comparison, the energy yield of MSW using incineration is 450-500 kWh/ton of MSW.

BIOGAS

Anaerobic digestion is a biological process in which bacteria breaks down organic matter within an airless environment, with biogas as the end product. Biogas derived from bagasse waste is comprised of approximately 60% methane (CH4), 40% carbon dioxide (CO2), and trace amounts of other gasses, including hydrogen sulfide (H2S).

Due to its high methane content, biogas can be used as a fuel for energy conversion devices. Alternatively, it can simply be flared, as the resulting carbon dioxide makes a lesser impact on global climate than methane.

Anaerobic digestion can occur within three different temperature ranges: psychrophilic, mesophilic, and thermophilic.

Psychrophilic digestion occurs at temperatures below 68°F and is usually associated with systems that operate at ground temperature. Psychrophilic digestion has the lowest biogas production rate of the three temperature ranges. Also, the production rate is susceptible to seasonal and diurnal fluctuations in temperature, making it difficult to predict how much biogas will be available.

The mesophilic temperature range is between 68°F and 105°F. The optimal temperature for mesophilic digestion is approximately 100°F. Digesters operating in the mesophilic range require constant heating in order to maintain a temperature of 100°F.

The thermophilic range is between 110°F and 160°F. The elevated temperature allows for the highest rate of biogas production and the lowest hydraulic retention time (HRT). The HRT is the amount of time material must remain in the digester before it is sufficiently processed. Digesters that operate in the thermophilic range require substantial amounts of energy to maintain the proper temperature and are prone to biological upset due to temperature fluctuations. To avoid upset, they require closer monitoring and maintenance. Another drawback is that the effluent is not odor free.

There is a variety of anaerobic digestion systems, choosing the appropriate system depends on many factors including local weather conditions, local water tables, organic waste collection techniques, storage capacity, and end use of the by-products.

Biogas Production

The addition of the BioCRUDE fungal technology, based on hydrolytic enzymes, to a digester, leads to an increased gas production up to 25 %. There is no additional significant investment or a change in the plant regime necessary for this enhancement. Besides an obvious decrease in the viscosity of the digester content, the shape of scum layers is restrained, and the whole process stabilized.

Biogas Technology

The main reasons for applying the BioCRUDE technology to the Biogas process are:

1. It is an effective method for the treatment of different types of waste (e.g. animals manure, household organic waste, waste from a food industry, sludge from wastewater treatment plants) in an environmentally friendly way.

2. A Biogas plant is the key element in reducing CO2 emissions by 50%. Applying Biogas technology will help to achieve the CO2 reduction target.

3. There is an improvement in the quality of fertilizers derived by digesting the raw manure which contains pathogens. These pathogens can be easily transferred to humans through agricultural products if the raw manure used directly on the field. Anaerobic digestion of animal manure improves the fertilizer quality from the hygienic point of view. Additionally, the solid residuals from biogas plant (fertilizers) can be easily spread on the field after the completion of the digestion process.

4. Anaerobic digestion reduces the offensive odor of biomass, minimizing the nuisance from odor and flies.

6. There is an expectation of achieving a potential reduction in the cost of biogas with continuous research and development. The goal is to make this technology profitable for the private sectors allowing the industry the takeover and achieve further developments in this technology.

7. To increasing the implementation of renewable energy use, especially after a decline in the oil production in this country. The aim is to make our systems self-dependent, thereby being impacted in a smaller way by changes in oil prices.

8. The Biogas process is an economic technology to treat organic waste, as compared to other treatment processes such as landfill disposal and incineration. There is a measurable monetary cost reduction in treating organic waste with a digestion process.

9. Biogas technology can be combined with the separation technology for manure. This combination has advantages for both farmers and biogas plants. The purpose of separation of manure is to refine nutrients in a concentrated form.

Socio-economic analysis of biogas plant

1. The construction cost of biogas process is high and it contributes significantly to the total cost of the plant. Therefore, constructing a biogas plant with high capacity will considerably reduce the cost of biogas. As a result, the higher the capacity of biogas plant, the lower the cost of biogas produced.

2. Transportation of biomass from source to biogas plant has a high contribution to the total cost of producing energy from this technology. The higher the capacity of biogas plant, the higher the transportation cost of biomass. In fact, transportation distance is higher for biogas plant with high capacity. However, the increase in the transportation cost is small compared to the savings in investment cost and biomass storage.

3. The suggested plan is to construct biogas plants with large capacity 800 tons of biomass/day in order to reduce the cost of biogas produced.

4. Biogas technology is not profitable from a traditional economic point of view. In the other hand, biogas process is very attractive from the socio-economic point of view which includes externalities (e.g. environmental and agricultural impacts) in monetary terms. This conclusion supports the fact that the main reasons for applying biogas technology are to reduce the environmental impacts (e.g. groundwater pollution and GHG emission) and to increase the benefit in agricultural and industrial sectors. The externalities can be best internalised by regulations which forced the different actors (e.g. farmers, industry, energy producers …etc) to treat waste in environmental friendly way, reduce GHG emission and prevent pollution. This will create a strong interest in biogas technology because social welfare will become a social duty.

5. R&D in biogas process is vital in order to perform further technological developments in this field. The aim is to increase the biogas yield and thereby reduce the cost. The cost can be reduced also by developing more effective and efficient pre-treatment processes which separate foreign materials (e.g. plastic bags and inorganic waste) from the digested biomass. The efficient separation process is important to increase the implementation of biogas plants in the future. For this reason, organic waste from household will be needed and this type of waste requires separation at the biogas plants.

The BioCRUDE Advantage

Based on this information, BioCRUDE Technologies has focused on research programs to develop biogas technology. BioCRUDE technology presents efficient, environment-friendly and economical solutions to waste reformation into renewable energy sources.

Urban centers suffer from nearly every woe that the BioCRUDE system addresses: organic waste and raw sewage disposal, pollution reduction, water purification, disease control, renewable energy sources, and a local power source for millions of off-grid households. Few products fit a market so exactly and become available at exactly the time they are needed, but that is certainly the case here.

Biogas technology has many environmental, agricultural and industrial applications. It is a method to treat organic waste in the environmentally friendly way. As well, the energy production from biogas contributes to GHG reduction. From a socio-economic point of view, biogas technology is profitable and promising technology due to its benefits for the environment, agriculture, and industry.